Crossfire event , coil near plug
The is a performance set up on this LS engine . 408 cid stroked . Running a Holley EFI stand alone unit .
The truck coughs up the intake and pops out the exhaust as Soon as the throttle is opened . Crank and cam signal present and in sink , I have checkedthe static timing with a timing light and it is correct . Holley doesn’t not believe it’s a faulty ECM but don’t have any ideas as to why it’s happening . has Any one been down this road before . Thanks in advance .
also steady compression at 185 on all cylinders . Swaed plugs wires and coils no chance . To me the ecm is firing the wrong cylinder at the wrong time .
Also this unit ran great for 2 weeks and then developed this problem .
Sounds like a lean condition. I hate modified vehicles.
Hi Jeff, I agree with Dave’s assumption that it’s lean. Have you verified that the fuel pressure is set to spec? Pull a fuel sample while you‘re there. Do you have the software to interface with this system? Perhaps there’s a fault? Can you verify KOEO MAP? Not sure which system you have but I’ve tuned many of these on a chassis dyno and a wide band sensor. Many moons ago, I used to turn…
thank you for your input , I have checked the fuel pressure and air fuel ratio during this issue . air fuel hangs out 16-17:1 fuel pressure stays were it has been set at 43 psi . I was blaming the lean air fuel mixture on the misfire event . I loaded a tune for open loop status only so it would never go into fuel control and it run off a base fuel calculations [ no change ] . what I have learned…
Jeff. I agree with what others are telling you, it does sound like it is a Lean Misfire. My suggestion would be to connect a Propane enrichment bottle up to the intake somewhere, then as you begin to open the throttle also give it a shot of propane. I have been using this method for years to isolate the exact cause of the misfire, this way, if it still misfires you need to move on to another…
Thank you for your input I will be sure to try the propane jim . If you dont mind explaining , how does a lean air fuel mixture cause coughing up a intake ? I have never been tought this yet and have not seen the issue before . Of coarse I like to know the deep theory of what is happening in the cylinder . Thank you !